Metal-containing exopeptidases

Riordan, J.F. 1974. Metal-containing exopeptidases. In Food related enzymes, ed. J.R. Whitaker. Advances in Chemistry Series 136. Washington, DC American Chemical Society. 

In the C-terminal domain are five helices in a closed bundle. This characteristic fold is typical of thermolysin-like peptidases. Clan MC contains metallocarbox-ypeptidases which belong to only one family (M14) which is divided into the subfamilies A, B and C. Typical for this clan is that one zinc ion is tetrahedrally coordinated by a water molecule, two histidine and one glutamate residues. Clan MF includes aminopeptidases that require cocatalytic zinc ions for their enzymatic activity. The well-known leucyl aminopeptidase has a two-domain structure bearing the active site in the C-terminal domain. Whereas exopeptidases of clan MG require cocatalytic ions of cobalt or manganese, clan MH contains the third group of metallopeptidases that also require cocatalytic metal ions, but here these are all zinc ions. The third clan in which cocatalytic metal ions are necessary is clan MF with zinc or manganese. Only one catalytic zinc ion is required for peptidases of clans MA, MB, MC, MD and ME. 

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